if you already know the name of the book you're looking for, it's pretty useful.

Hm. I checked with everlasting and with "everlasting man" in quotes. The latter is the title of a work I bought from ebooks.faithlife (formerly Vyrso) just recently, and it hits just there and in a remark about its absence in the Collected Works of Chesterton (which shows you can search the former Vyrso store better than its current search engine - kudos for that!) - but the word everlasting should yield titles from probably all the stores. In fact the custom google search brings up obscure hits in the description texts (and those from logos.com mostly and one from verbum.com).

Does this need some tweaking in the search syntax (and if so, how can we do that?)

Coincidentally enough, I made this in the shortcuts app on iOS yesterday - you type in what you want to search and it opens a search on those three sites (3 tabs open at the same time, filtered to show 60 items and hide unread items)

It's certainly promising but it doesn't seem to be finding everything. I just tested it with an author's name. "Bill Myers" only returns 8 hits but there are far more than 8 of his books available. Cf. the not very helpful list: https://ebooks.faithlife.com/search?query=Bill%20Myers

fwiw this is the same result I get with "Bill Myers" site:https://ebooks.faithlife.com/ so I guess it's Google's fault. Bing gives me 26 results with that same string. All very perplexing.

Thank you Mark, this is very helpful. This has long been a pet peeve of mine. I admit I don't understand the ins and outs of web based commerce, but it boggles my mind that a company would make a customer search through multiple websites just to see if they offer a product. I know there is history as to why they have multiple sites, but I don't understand why they don't make it as easy as possible for the consumer to find what they are looking foor. I appreciate you doing the legwork Mark.